Finland knocked the United Kingdom out of the first-place spot in 2007, and Singapore moved all the way from 16th place in 2006 to third in 2007

Unlike the majority of countries ranked in the index, however, the United States received a lower ranking in 2007 compared with the year before, moving from fourth place to 13th. Sarbanes-Oxley is partly to blame, the Milken Institute says.

According to the press release:

The Opacity Index measures five factors: corruption, legal system efficiency, economic and enforcement policies, accounting standards and regulatory effectiveness.... Higher levels of opacity in each of the CLEAR factors indicate poorly functioning governments, which increases the cost of doing business, as well as the risk.

Given those factors and what I've read in the past several months, the state of the legal system and the perceived ineffectiveness of other regulations in the United States probably didn't help the ranking, either.